Trading in or Recycling Smartphones

I'm curious what options are out there for your old smartphones. (I'm in europe at the moment, but insight from the us / asia is good too)

Say you bought an unlocked smartphone last year off amazon or whatever.

Now you want to "upgrade". What do you do with the old one? (apart from the usual: hand it to grandma, sell it to a friend, put it in a box in the attic, use it as a tv remote)

And what if it's super old and crappy, and you're just concerned with recycling it?

Considering the rare earths and metals that go into these things, and how you can't just throw them into a landfill even if you can't recover parts from them, you'd think there would be a global and easy to find initiative to get them off your hands. But so far it seems you either have to sell it second hand or hope your carrier might take it.

What happens to the many thousands of smartphones at the bottom of the chain each year? Do they somehow end up in africa where some kid melts them over an open fire, inhaling the pollutant gasses and poisoning the land, to sell off the leftover metal in the circuit boards?

I tend to keep them, I have a small collection of them. Mind you I like to mess with different ones so there are some oddities in my collection including a Firefox phone and a Nokia Windows Phone. I have an old Samsung I like to flash to different images just to mess about. I did read somewhere about turning your old smartphone into a IP security camera.

Yeah, finding useful uses for old smartphones is probably the most lucrative option in lieu of properly disposing of them in exchange for some reward.

I'm not sure how long a smartphone would last if repurposed for a continuous task, e.g. plugging it in and using it as a 24/7 security camera. Or using it as a router or some kind of sensor controller.

It also sucks how most phones don't have removable batteries or SD card slots.